Medium
@asymmetric-effort/specifyjs: CSS expression sanitization is bypassable in renderToString
Type: advisorySources: OSV
SpecifyJS is a declarative TypeScript user interface framework. Prior to version 0.2.136, CSS value sanitization stripped `expression(` and `url(javascript:` using simple regex, but could be bypassed with CSS unicode escapes (`\65xpression(`), null bytes, or CSS comments (`exp/**/ression(`). These CSS injection vectors only work in legacy browsers (IE6-IE10). SpecifyJS targets modern browsers. Starting in version 0.2.136, CSS sanitization now normalizes unicode escapes and strips CSS comments before pattern matching. Also checks for `behavior:`, `-moz-binding`, and `-o-link` patterns.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2026-50290
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 3 Nov 2026, 15:10 UTC · Revision 1
Source evidence
@asymmetric-effort/specifyjs: CSS expression sanitization is bypassable in renderToString
core-osv · Original sourcePublished 21 Aug 2026, 19:55 UTC
SpecifyJS is a declarative TypeScript user interface framework. Prior to version 0.2.136, CSS value sanitization stripped `expression(` and `url(javascript:` using simple regex, but could be bypassed with CSS unicode escapes (`\65xpression(`), null bytes, or CSS comments (`exp/**/ression(`). These CSS injection vectors only work in legacy browsers (IE6-IE10). SpecifyJS targets modern browsers. Starting in version 0.2.136, CSS sanitization now normalizes unicode escapes and strips CSS comments before pattern matching. Also checks for `behavior:`, `-moz-binding`, and `-o-link` patterns.
osv:CVE-2026-50290
Complete source record
{
"id": "73994e11e4ef4fe0444c367c08bafbaf7cce6c5be123f88eee61aff86c956f96",
"url": "https://osv.dev/vulnerability/CVE-2026-50290",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "@asymmetric-effort/specifyjs: CSS expression sanitization is bypassable in renderToString",
"summary": "SpecifyJS is a declarative TypeScript user interface framework. Prior to version 0.2.136, CSS value sanitization stripped `expression(` and `url(javascript:` using simple regex, but could be bypassed with CSS unicode escapes (`\\65xpression(`), null bytes, or CSS comments (`exp/**/ression(`). These CSS injection vectors only work in legacy browsers (IE6-IE10). SpecifyJS targets modern browsers. Starting in version 0.2.136, CSS sanitization now normalizes unicode escapes and strips CSS comments before pattern matching. Also checks for `behavior:`, `-moz-binding`, and `-o-link` patterns.",
"evidence": "osv:CVE-2026-50290",
"products": [],
"severity": "medium",
"structured": {
"id": "CVE-2026-50290",
"aliases": [
"CVE-2026-50290",
"GHSA-93q6-wwjh-jc6h"
],
"metrics": [
{
"type": "CVSS_V4",
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/asymmetric-effort/specifyjs",
"type": "GIT",
"events": [
{
"introduced": "0"
},
{
"fixed": "25d1fb491d99479efdf501f5f75e0bb80c908f0a"
}
],
"database_specific": {
"extracted_events": [
{
"range": [
{
"introduced": "0"
},
{
"fixed": "0.2.136"
}
],
"source": "AFFECTED_FIELD",
"strategy": "StringRangeExpression"
},
{
"range": [
{
"fixed": "25d1fb491d99479efdf501f5f75e0bb80c908f0a"
}
],
"source": "REFERENCES_COMMIT"
},
{
"range": [
{
"introduced": "0"
},
{
"fixed": "0.2.136"
}
],
"source": "DESCRIPTION"
}
]
}
}
],
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],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-50290.json"
}
}
],
"modified": "2026-10-28T02:30:29.961547427Z",
"provider": "osv",
"references": [
"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/50xxx/CVE-2026-50290.json",
"https://github.com/asymmetric-effort/specifyjs/security/advisories/GHSA-93q6-wwjh-jc6h",
"https://nvd.nist.gov/vuln/detail/CVE-2026-50290",
"https://github.com/asymmetric-effort/specifyjs/commit/25d1fb491d99479efdf501f5f75e0bb80c908f0a"
],
"provider_metadata": {
"cwe_ids": [
"CWE-79"
],
"cna_assigner": "GitHub_M",
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/50xxx/CVE-2026-50290.json"
}
},
"related_cves": [
{
"value": "CVE-2026-50290",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 496694,
"published_at": "2026-08-21T19:55:51.086+00:00"
}